1. Field of the Invention
The present invention relates to an optical switch for changing connection of signal light, particularly to an optical switch in which deflection of light by a movable mirror is used.
2. Description of the Related Art
U.S. Pat. Appln. Publication No. 2002/0196520A1 discloses an optical switch for wavelength division multiplexing (WDM) transmission, which is capable of switching connections between input optical fibers and output optical fibers via which signals having multiplexed wavelengths are transmitted for each wavelength. The device is applicable to a multiplexer (MUX), demultiplexer (DEMUX), and optical switch in accordance with the numbers of input optical fibers and output optical fibers.
In the optical switch, the light from the input optical fiber is formed into parallel light, split by a grating, formed into converging light through lenses, and applied to a MEMS mirror for each wavelength. By changing a direction of the MEMS mirror, reflected light traces a path different from that of the input light, and is combined with the output optical fiber that is disposed in a position different from that of the input optical fiber. Accordingly, the optical fiber that is an output destination can be selected by the changing of the direction of the MEMS mirror for each wavelength.
In the optical switch (the switch operates) in which specific light entering, that is, combining with the output optical fiber is switched to another output optical fiber from the current output optical fiber, unless the output optical fiber before the switching is adjacent to that after the switching, the light from the input optical fiber is combined with an intermediate output fiber that is not related to the switch operation in the process of the changing of the direction of the MEMS mirror.